<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>css作业-css布局2</title>
<link href="css06.css" rel="stylesheet" type="text/css">
</head>

<body>
<header id="header">
  <h1>作业1</h1>
  <div class="box1">
    <div class="item1"></div>
    <div class="item2"></div>
    <div class="item3"></div>
  </div>
  <h1>作业2</h1>
  <div class="box2">
    <div class="son">
      <div class="item1"></div>
      <div class="item2"></div>
      <div class="item3"></div>
    </div>
  </div>
	<h1>作业3</h1>
	<div class="box3">
	<div class="son">
		<div class="item1"></div>
		<div class="item">
		<div class="item2"></div>
		<div class="item3"></div>
		</div>
		</div>
	</div>
</header>
</body>
</html>
